This article lists the genera of the Archaea. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI). However, in the List provided below, GTDB has precedence unless otherwise noted.

Phylogeny

National Center for Biotechnology Information (NCBI) taxonomy was initially used to decorate the genome tree via tax2tree. The 16S rRNA-based Greengenes taxonomy is used to supplement the taxonomy particularly in regions of the tree with no cultured representatives. List of Prokaryotic names with Standing in Nomenclature (LPSN) is used as the primary taxonomic authority for establishing naming priorities. Taxonomic ranks are normalised using phylorank and the taxonomy manually curated to remove polyphyletic groups. Cladogram was taken from the GTDB release 08-RS220 (24th April 2024). The position of clades with a "question mark" are based on the additional phylogeny of the 16S rRNA-based LTP_12_2021 by The All-Species Living Tree Project.

Archaea incertae sedis

Phylum "Microcaldota"

Class "Microcaldia"

Order "Microcaldales"

Phylum "Undinarchaeota"

Class "Undinarchaeia"

Order "Undinarchaeales"

Phylum "Altarchaeota"

Class "Altarchaeia"

Order "Altarchaeales"

Phylum "Iainarchaeota"

Class "Iainarchaeia"

Order "Forterreales"

Order "Iainarchaeales"

Phylum "Micrarchaeota"

Class "Micrarchaeia"

Order "Norongarragalinales"

Order "Micrarchaeales"

Order "Anstonellales"

Order "Fermentimicrarchaeales"

Order "Burarchaeales"

Order "Gugararchaeales"

Phylum "Huberarchaeaota"

Class "Huberarchaeia"

Order "Huberarchaeales"

Phylum "Aenigmatarchaeota"

Class "Aenigmatarchaeia"

Order "Aenigmatarchaeales"

Phylum "Nanohalarchaeota"

Class "Nanohalarchaeia"

Order "Nanohydrothermales"

Order "Nucleotidisoterales"

Order "Nanohalarchaeales"

Class "Nanohalobiia"

Order "Nanohalobiales"

Phylum Nanobdellota

Class Nanobdellia

Nanobdellia incertae sedis

Order JAPDLS01

Order "Jingweiarchaeales"

Order Nanobdellales

Order "Tiddalikarchaeales"

Order "Parvarchaeales"

Phylum Promethearchaeota

Promethearchaeota incertae sedis

Class "Thorarchaeia"

Order "Thorarchaeales"

Class "Njordarchaeia"

Order "Njordarchaeales"

Class "Sifarchaeia"

Order "Borrarchaeales"

Order "Sifarchaeales"

Class "Wukongarchaeia"

Order "Wukongarchaeales"

Class "Heimdallarchaeia"

Order "Hodarchaeales"

Order "Gerdarchaeales"

Order "Heimdallarchaeales"

Class "Odinarchaeia"

Order "Odinarchaeales"

Class "Jordarchaeia"

Order "Jordarchaeales"

Class "Baldrarchaeia"

Order "Baldrarchaeales"

Class "Hermodarchaeia"

Order "Hermodarchaeales"

Class Promethearchaeia

Order "Helarchaeales"

Order Promethearchaeales

In GTDB as order CR-4

Phylum Thermoproteota

Thermoproteota Incertae sedis

Class JANJXX01

Order "Panguiarchaeales"

Class "Korarchaeia"

Order "Korarchaeales"

Class "Bathyarchaeia"

Order "Hecatellales"

Order "Bathyarchaeales"

Class Nitrososphaeria_A

Order "Caldarchaeales"

Class Nitrososphaeria

Nitrososphaeria Incertae sedis

Order "Geothermarchaeales"

Order "Conexivisphaerales"

Order Nitrososphaerales

Class "Methanomethylicia"

Methanomethylicia incertae sedis

Order "Nezhaarchaeales"

Order "Culexarchaeles"

Order "Methanomethylicales"

Class Thermoproteia

Order "Gearchaeales"

Order Thermofilales

Order Thermoproteales

Class "Sulfolobia"

Order "Marsarchaeales"

Order Sulfolobales

Phylum Methanobacteriota_A

Class "Methanococcia"

Order Methanococcales

Phylum "Hadarchaeota"

Class "Persephonarchaeia"

Class "Hadarchaeia"

Order "Hadarchaeales"

Phylum Methanobacteriota_B

Class "Theionarchaeia"

Class Thermococci

Order "Methanofastidiosales"

Order Thermococcales

Phylum "Hydrothermarchaeota"

Class "Hydrothermarchaeia"

Order "Hydrothermarchaeales"

Phylum "Methanobacteriota"

Class Methanopyri

Order Methanopyrales

Class Methanobacteria

Order Methanobacteriales

Phylum Thermoplasmatota

Thermoplasmatota incertae sedis

Class "Izemarchaea"

Order "Thermoprofundales"

Class "Poseidoniia"

Order MGIII

Order "Poseidoniales"

Class Thermoplasmata

Order "Lunaplasmatales"

Order "Proteinoplasmatales"

Order "Yaplasmatales"

Order "Gimiplasmatales"

Order "Sysuiplasmatales"

Order Methanomassiliicoccales

Order "Halarchaeoplasmatales"

Order "Aciduliprofundales"

Order Thermoplasmatales

Phylum Halobacteriota

Halobacteriota incertae sedis

Order "Methanoflorentales"

Class Methanomicrobia

Order Methanomicrobiales

Class "Methanoliparia"

Order "Methanoliparales"

Class "Archaeoglobia"

Order "Mnemosynellales"

Order Archaeoglobales

Class "Syntropharchaeia"

Order "Syntropharchaeales"

Order "Alkanophagales"

Class Methanocellia

Order Methanocellales

Class Methanosarcinia

Order Methanosarcinales_A

Order Methanotrichales

Order Methanosarcinales

Class "Hikarchaeia"

Order "Hikarchaeales"

Class "Methanonatronarchaeia"

Order "Methanonatronarchaeales"

Class Halobacteria

Order Halorutilales

Order Halobacteriales